Combination lock



4 Sheets-Sheet 1 C. P. COOK COMBINATION LOCK I z ut-3 456-! DEF Dec. 12, 1967 Filed Dec.

INVENTOR COLEMAN P 600K ATTORNEYS 1967 c. P. cooK 3,357,216

COMBINATION LOCK Filed Dec. 9, 1965 4 Sheets$heet 2 INVENTOR COLEMAN P 600 ATTORNEYS Dec. 12, B6? c. P. COOK COMBINATION LOCK 4 Sheets-Sheet 3 Filed Dec.

CQAEMAN i? @(W jBY ATTORNEYS C. P. COOK Dec. 12, 1967 COMBINATION LOCK 4 Sheets-Sheet Filed Dec. 9, 1965 INVENTOR COLEMAN F? COOK //4 w m //4 /20 //4 m &&%% I 1' ATTORNEYS United States Patent 3,357,216 CQMBINATION LOCK Coleman P. Cook, finite 320, 1256 Connecticut Ave. NW., Washington, D.C. 20036 Filed Dee. 1%5, Ser. No. 512,660 9 Claims. (Cl. 70-613) This invention relates to a combination lock and particularly to a novel, combination-controlled lock release mechanism, releasable only after manipulation of the combination devices in a predetermined manner.

The combination lock shown and specifically described herein is embodied in a door lock, merely for purpose of illustration. It is to be understood, however, that the principles of the invention may be embodied in other locks for use in other environments than doors leading to rooms or buildings.

In general, the lock mechanism comprises a retractable bolt and latch means normally holding the bolt against retraction. An inside handle or knob may be turned to release ancl retract the bolt without manipulation of the combination mechanism but the outside or front handle or knob cannot be operated to retract the bolt unless the proper combination has been set into the release mechanism. The release mechanism comprises a plurality of duplicate devices, all of which must be in a predetermined condition before the bolt can be withdrawn. Each of the individual mechanisms comprises a cylindrical plunger extending through an opening in aslide plate. Each of the cylinders is provided with tangential grooves spaced axially along the cylinder and respectively oriented at different angles around the axis of the cylinder. Setting mechanism is provided which advances a selected cylinder in a step-by-step manner through the opening in the plate until a particular groove is in the plane of the plate. A slot extends from the opening in the plate in the direction of movement of that plate so that when the proper groove is aligned with that slot, the plate can then slide in a direction past the cylinder with the slot therein embracing the cylinder groove. Obviously, a plurality of such cylinders must be individually operated until each of them is in the proper position whereupon a spring moves the plate toward releasing position and withdraws a latch from holding engagement with the bolt of the lock and the latter can then be withdrawn.

Each of the cylinders is mounted for rotation about its axis and provided with means for holding it in a selected position of rotation. Thus, by presetting any selected cylinder or cylinders to a desired angular position, the extent of axial movement necessary to align the proper groove with the slot can be preset and that particular cylinder must then be moved through the preset number of discrete steps to release the lock.

The plate is also provided with means whereby enforced movement thereof in a direction opposite its latch releasing movement will reset the cylinders to their starting positions and return the lock to a locked condition. Furthermore, any attempt to enforce movement of the slide plate in a latch releasing direction for the purpose of experimenting with the cylinders, results in blocking movement of the cylinder advancing means whereby to prevent experimentation in an effort to determine the proper combination.

It is, therefore, a principal object of this invention to provide a combination lock that is simple in construction and compact.

It is another object of the invention to provide a combination lock wherein the mechanism can be easily returned to locked condition by a simple manipulation Another object is to provide such a combination lock having a minimum number of parts but wherein an extremely wide variety of combinations is possible.

An additional object is to provide a combination lock of the type set forth wherein it is impossible to determine the combination by experimentation.

Further and additional objects and advantages will become apparent to those skilled in the art as the description proceeds with reference to the accompanying drawings wherein:

FIG. 1 is a front elevational view of the combination lock of the present invention;

FIG. 2 is an enlarged rear elevation of the combination lock of FIG. 1;

FIG. 3 is an enlarged fragmentary vertical sectional view taken on the line 3-3 of FIG. 1;

FIG. 4 is a vertical sectional view taken on the line 44 of FIG. 3;

FIG. 5 is a horizontal sectional view taken on the line 55 of FIG. 4;

FIG. 6 is a horizontal sectional view taken on the line 6-6 of FIG. 4;

FIG. 7 is a fragmentary horizontal sectional view taken of the line 7-7 of FIG. 3;

FIG. 8 is a fragmentary vertical sectional view taken on the line 8-8 of FIG. 3;

FIG. 9 is an exploded perspective view of the operating cams associated with the front and rear handles;

FIG. 10 is an isometric view of one of the cylinder ratchet bars of the present invention;

FIG. 11 is an isometric view of one of the pawls;

FIG. 12 is an isometric view of one of the lock cylinders; and

FIGS. 13 through 16 are vertical sectional views through the lock cylinder taken on the lines 13-13 through 16 16 of FIG. 12.

Referring tothe drawings and particularly FIGS. 1 and 2, there is shown therein a combination lock mechanism embodying the present invention as adapted to a door lock. The front or outside of the lock is shown in FIG. 1 wherein a frame generally designated at 2 is provided with a sliding bolt 4 and an outer knob 6. Also accessible from the front of the lock is a group of pushbuttons arranged in the illustrated embodiment in three vertical rows 8, 10 and 12. As shown, there are three pushbuttons in each vertical row, thus providing nine pushbuttons in all. For convenience of description, the individual pushbuttons of each vertical row are designated by the same reference numerals. FIG. 2 illustrates the rear or inner face of the lock with a cover plate removed and shows the frame 2 with an inner knob 14 and a plurality of combination setting devices 16 accessible at the inner side of the lock, there being one for each pushbutton. Each of the devices 16 is a serrated rotatable head member, to be more fully described later, but each is held in a selected angular position of rotation by a suitable indexing spring 18 engaging a selected notch of serration 20 in the head device. Each is also provided with a screwdriver slot 22 by which it may be rotated in an obvious manner, an index or marker 24 and the frame plate on which they are mounted is provided with a fixed indicator mark 26. To set the combination, the selected heads are rotated, for example clockwise, a desired number of steps. When any one of the heads is positioned with its index 24 adjacent the fixed marker 26, that particular mechanism, corresponding to one of the pushbuttons 8, 10 or 12, need not be manipulated since that mechanism is already set to permit the slide plate to move, as will be more fully described.

Referring next to FIG. 4, which is a vertical sectional view through the lock, the bolt 4 is shown as being slidably mounted in the frame 2 by means of slots 30 therein and pins 32 on the frame 2. The bolt 4 is provided with a notch 34 in which a latch 36 is engageable to prevent retraction of the bolt 4 toward the right as seen in FIG. 4.

The latch 36 is pivotally mounted on the frame 2 by means of a suitable pivot pin 40 and is urged by spring 42 in an upward direction to engage in the notch 34 of the bolt. A slide plate 44 is slidably mounted on a fixed frame plate 38 by means of slots 46 in the slide plate and pins 48 on frame or fixed plate 38. The slide plate 44 carries a stud 50 on which the spring 42 is mounted and also carries a pin 52 fixed thereon engaging an extension or car 54 on the latch 36. The frame plate 38 is provided with an upper flange 56 overlying but spaced from a similar flange 58 on slide plate 44. A leaf spring 60 reacts between the fianges 56 and 58 to constantly urge the slide plate 44 downwardly, as seen in FIG. 4. As shown in FIG. 4, the nine combination setting mechanisms, which will be more fully described later, are all set in such position that the slide plate 44 is free to move downwardly. However, the slide plate cannot move downwardly since it is held in its upper position by a cam element 62 fixed on the shaft 64 which carries the outer knob 6. The cam 62 is more clearly shown in FIGS. 8 and 9. Also shown in FIGS. 3 and 9 is an inner shaft 66 which carries the inner door knob 14 fixed thereon. A pilot pin 68 holds the shafts 64 and 66 in alignment but permits free relative rotation. As also shown, the shaft 64 is provided with an axially facing recess 70 (FIGS. 8 and 9) into which a projection 72 on the shaft 66 projects. The recess 70 is of much greater angular extent than the projection 72 so that either shaft may be rotated through a predetermined angle independently of the other one.

Fixed on shaft 66 is an inner cam 74 having a cam surface 76 engageable with the portion of latch 36 that extends into the notch 34 of the bolt 4. The exploded perspective view of FIG. 9 illustrates the relationship of the parts.

The bolt 4 is also provided with a notch 78 on its inner or rear face and with a forwardly projecting pin 80 fixed thereto and extending from its front face. The cam 74 is provided with a forwardly extending pin 82. Since the inner knob 14 can be rotated through a predetermined angle without actuating the outer knob 6, it can be seen from FIG. 4 that the inner knob can be rotated counterclockwise, at which time the cam surface 76 will push the latch 36 downwardly away from bolt 4 and thereafter pin 82 will enter the notch 78 in the bolt and continued rotation in a counterclockwise direction will retract the bolt 4 toward the right without necessarily enforcing any movement of slide plate 44. Thus, the door can be opened from the inside without operating the combination lock mechanisms.

If any attempt is made to open the door from the outside while the combination lock mechanisms hold the slide plate 44 in its upper position, the device will function to prevent such opening. For example, if the shaft 64 is turned counterclockwise, as seen in FIG. 4, it will withdraw cam 62 from beneath flange 58 of the slide plate but the spring 69 cannot then lower that plate and spring 42 thus holds latch 36 in holding engagement with the bolt 4. Continued rotation of the outer shaft 64 will rotate the member 90, fixed thereon, until the upper or longer finger thereof engages the pin 80 on the bolt 4. However, continued rotation is not possible since the bolt 4 is latched in its locking position. It is to be noted that initial rotation of the outer shaft 64 withdraws the cam 62 from holding relation to the flange 58 of the slide plate 44.

If, however, the combination lock mechanisms are in the position shown in FIG. 4, the lock may be released by the outer shaft 64 by rotating the same counterclockwise, as seen in FIG. 4. Initial rotation of the shaft retracts cam 62 in the manner described and releases the slide plate to the action of spring 60. The slide plate is then pushed downwardly and since it carries spring 42 and pin 52, it will withdraw the latch 36 downwardly from the notch 34, whereupon the upper finger can then engage pin 80 on the bolt and further movement will retract the bolt toward the right. The pin 80 can enter the slot 91 and lower finger 93 will then return the bolt 4 to its locking position upon reverse rotation of shaft 64. If desired, a spring, not shown, may be provided to project the bolt 4 to the left.

The nine mechanisms shown which are operated by the pushbuttons 8, 10 and 12 are all identical so only one will be described in detail. Referring first to FIGS. 12 through 16, the heart of each mechanism comprises a cylinder 92 having pairs of grooves in its periphery. As shown in those figures, a first pair of grooves 94 are formed with their bottoms in parallel relation and tangential to the axis of the cylinder 92 (FIG. 13). The grooves 94 are each in the same radial plane as are the grooves of each of the other pairs, to be described. A second pair of grooves 96 (FIG. 14) are formed in the cylinder 92 axially spaced from the grooves 94 and also arranged at a different angle about the axis of the cylinder 92. In. like manner, pairs of grooves 98 and 100 are formed in the cylinder 92, each pair of grooves being axially spaced from the others and each being at a different angle about the cylinder axis. Thus, as the cylinder is rotated about its axis through the five steps determined by the springs 18 of FIG; 2, a selected pair of the grooves can be brought into vertical position. As shown in FIGS. 12 and 13, the pair of end grooves 94 is in the vertical position whereas each of the others extends at some other angle.

The cylinder 92 is also provided with a central axial bore 102 and a transverse bore 104 near one end thereof. Referring now to FIG. 3, each of the rotatable heads 16, previously described, is formed on the end of a supporting shaft 106 and held in place in the frame by a split ring 108. Each of the supporting shafts 106 is hollow, as shown, with its outer end rotatably supported by a stud 110 fixed in the outer frame plate 2. Each supporting shaft 106 is further provided with axially extending diametrically opposed elongated slots 112 and a cylinder 92 is slidably mounted on each of the supporting shafts 106. A pin 114 extends through the slots 112 and the transverse bore 104 in each cylinder to hold the cylinder against rotation relative to the shaft 106 but permitting axial sliding movement therealong. A compression spring 116 in the hollow shaft 106 bears at one end against the pin 114 and thus constantly urges the cylinder 92 toward the right, as seen in FIG. 3. A ratchet bar device 118 (see also FIG. 10) extends axially along the upper surface of the cylinder 92 and is provided with end legs 120 which, in turn, are provided with openings 122, which slidably embrace the supporting shaft 106. The distance between the legs 120 is substantially equal to the length of the cylinder 92 whereby the latter and the ratchet bar mechanism slide along the shaft 106 as a unit but wherein the cylinder is free to turn between the legs 120. The ratchet bar 118 is provided with ratchet teeth 124 on its upper surface, the axial spacing of the teeth being equal to the axial distance between the pairs of grooves 94- 100. The pushbutton 10 is provided with a rigid shank 126 (see also FIG. 7) slidable through an opening in the outer frame plate 2 and through an aligned opening in the intermediate fixed plate 38. Pivoted to one side of the shank 126 is a pawl 128 having a depending tooth 130 substantially complementary to and engageable with the ratchet bar teeth 124. An anchor block 132 is fixed to the inner frame plate 2 and has secured thereto a leaf spring device provided with a pair of fingers 134 and 136. The pawl 128 has a transverse groove 138 in its free end and into which the end of spring finger 134 extends. As shown most clearly in FIG. 3, the spring finger 134 is looped upwardly between the pawl 128 and anchor block 132. It will be apparent that the corresponding pushbutton can be pushed inwardly while the looped spring finger 134 yields even though resisting such movement. The parts are so dimensioned that each pushbutton can be pushed inwardly a distance sufficient to force ratchet bar 118 and its associated cylinder 92 to the left through one discrete step equal in length to the axial distance between the pairs of grooves. A second or holding pawl 140 is pivotally carried by a block 142 mounted on the outer frame plate 2 and may be identical in construction to the pawl 128 already described. The spring finger 136, however, extends almost directly from anchor block 132 into the slot 138 of holding pawl 130 since the latter merely swings up and down without any movement in the axial direction. Thus, it can be seen that each depression of a pushbutton will advance its associated cylinder 92 to the left through one discrete step of movement and the holding pawl 140 will hold the ratchet bar and cylin der 92 in that advanced position while looped spring finger 134 returns the pushbutton and its pawl 128 to the retracted position shown in FIG. 7. It is to be noted that spring finger 134 also permits pawl 128 to rise and fall as it passes over ratchet bar teeth 124 while always urging the pawl tooth 130 downwardly.

Let it be assumed that some of the cylinders 92 have been rotated through one or more steps from the position shown in FIG. 4. In FIG. 4, the end grooves 94 at the inner ends of the cylinders are in the vertical position and slide plate 34 is free to move downwardly. However, if one or more cylinders is rotated from its position in FIG. 4, the grooves 94 will be at such an angle that they will block downward movement of the plate 34. If that cylinder has been turned through two angular steps, advancement by means of its pushbutton through two discrete steps will then position the proper pair of grooves in the plane of the slide plate 34 so that the grooves then in that plane are in the position as shown in FIG. 4.

Referring now to FIG. 4, the slide plate 34 is provided with a plurality of openings 144 through which the cylinders 92 extend. Corresponding openings are provided in the fixed frame plate 38. The openings 144 extend downwardly from each cylinder 92 and are of sufiicient width therebelow so that the plate 44 can be moved upwardly irrespective of the positions of any of the cylinders. However, extending upwardly from each opening 44 is a somewhat narrower slot 146 of a width only slightly greater than the distance between the bottoms of the pairs of grooves 94460. The ratchet bars 118 extend through the slots 146 and the plate 44 is provided with enlarged openings above the slot 146, to accommodate the pushbutton shanks 126 and pawls 128 and 146, all as clearly shown in FIG. 4. It is to be noted, however, that the openings 144 adjacent the to s of the cylinders 92 provide enough clearance for the plate 44 to move downwardly a very short distance before engaging the periphery of a cylinder 92. In like manner, the openings through the slide plate 44 through which the pushbutton shanks 126 pass are provided with a lower edge 148 very close to the upper surface of the shank 126. As long as the cam 62 holds the plate 44 in the position shown in FIG. 4, there is clearance below the edge 148 for the shanks 126 to move. However, if one were to attempt to feel the position of cylinders 92 by partially rotating the outer shaft 64, the plate 44 would be lowered sufiiciently for the edge 148 to block any attempt to depress a pushbutton. Thus, all the necessary pushbuttons must be manipulated through the preset number of steps before any attempt is made to retract the bolt 4. Once the outer knob is partially turned further movement of all pushbuttons is blocked.

After the pushbuttons have been manipulated in the proper manner to set all cylinders in their required posi tion for the plate 44 to move to latch releasing position, the mechanism can be reset to a locked condition without disturbing the presetting of the necessary combination. Let it be assumed that a combination has been set up and the required pushbuttons depressed so that the door can be opened from the outside. Thereafter, either inner or outer knob may be rotated in a direct opposition to that necessary to retract the bolt 4 and effect resetting of the cylinders to the starting end of their sliding movement. This is accomplished by the cam 62 previously described. From FIGS. 4, 8 and 9 it can be seen that the cam 62 is provided with one long lobe 150 that normally rests adjacent a rib 152 on the flange 58 of slide plate 44. As previously described, the cam 62 must be rotated in a counterclockwise direction before the bolt 4 can be retracted. However, if it is rotated in a clockwise direction to the position indicated by the upper dotted line showing of FIG. 8, the slide plate 44 will be lifted slightly from its normal position. Referring again to FIG. 4, it will be seen that the lower ends of the openings 144 in slide plate 44 are provided with shoulders 154 at the upper ends of the slots 146 for the next cylinder therebelow. These shoulders, at their inner ends, extend inwardly to underlie the edges of both pawls 128 and 149 so that upward movement of the plate 34 will lift both pawls out of engagement with ratchet bar 118 and thus release the ratchet bar and cylinder to the action of spring 116, whereupon the cylinders are returned to their starting position and the bolt cannot again be retracted until the pushbuttons have been again manipulated to set up the proper combination.

The resetting just described can be accomplished by either the inner or outer door knobs. Rotation of the outer door knob in the proper direction will directly effect rotation of the cam 62 to lift plate 44. If the lock is to be reset to a locked condition by means of the inner knob, the same is rotated along with itsshaft 66 in a clockwise direction as viewed in FIG. 8, for example. The first part of that rotation merely takes up the lost motion of projection 72 in recess 70. This rotates the cam 74 in a clockwise direction in which it has no effect on the latch 36 nor bolt 4. However, when projection 72 reaches the end of the recess 70 it engages a shoulder 156 on the front or outer shaft 64 and continued rotation then rotates the shaft 64 and cam 62 in a clockwise direction, as previously described.

Obviously, the mechanism described herein is capable of being set up for many diverse types of code or combination. For example, let it be assumed that the desired combination is to be identified by the code BUTTER 9. To set the lock for this combination, the heads 16 are manipulated in the following manner. The head under the letter B is rotated clockwise one step, the head under letter U is rotated one step clockwise, the head under letter T is rotated two steps clockwise, the head under letter E is rotated one step clockwise, the head under letter R is rotated one step clockwise, and the head under numeral 9 is rotated one step clockwise. All other heads are left in the position wherein their index marks 24 are adjacent the fixed indicators 26. All of the heads 16 that have been rotated will have rotated their corresponding cylinders 92 through one or more angular steps. Now, to unlock the door, the pushbuttons are mainpulative so as to spell out the combination code, as identified by the legends appearing above the pushbuttons, and in doing so will have advanced each cylinder the proper distance to align its vertical grooves with the slots 146 in slide plate 44 so that the bolt can then be retracted in the manner already described. Clearly, the combination can be changed simply and rapidly at any time, it only being necessary to select a desired code and to sequentially rotate the heads 16 in the manner described to spell out that code. Obviously, a code word or code number may be selected that requires manipulation of any desired number of pushbuttons and through any desired number of steps for each.

As best shown in FIG. 6, the pins 48 which guide slide plate 44 also hold inner and outer frame plates 2 in fixed spaced relation to fixed plate 38 by means of spacer blocks 158, shoulders 160, and sleeves 162. The sleeves 162 hold slide plate 44 against the inner face of fixed 7 plate 38. Heads 164 hold inner frame plate 2 against sleeves 162.

While a single specific embodiment of the invention has been shown and described herein, it is to be understood that the same is merely illustrative of the principles of the invention and that other embodiments are to be included within the scope of the patent, limited only by the scope of the appended claims.

I claim:

1. In a combination lock having a retractable bolt and means normally holding said bolt against retraction, the improvement comprising; a plate mounted for movement in the plane containing its edges and having means for releasing said bolt for retraction when said plate moves in one direction; at least one opening through said plate and a slot of less width than said opening and extending therefrom in the direction of movement of said plate; a member extending through said opening in a direction substantially perpendicular to said plate; means for moving said member in said opening through a selected number of discrete steps; the dimension of said member in a direction transverse to said slot being greater than the width of said slot; tangential groove means in said member at a predetermined position therealong whereby movement of said member through a predetermined number of said discrete steps will place said groove means in said plane, and in alignment with said slot to permit said plate to slid past said member in a latch releasing direction with said slot embracing said member at said groove means.

2. The lock defined in claim 1 wherein said member is rotatable about an axis generally perpendicular to said plate; means for rotating'said member about said axis and for holding the same in a selected one of a plurality of angular positions; there being a plurality of said tangential groove means on said member, axially spaced therealong at distances corresponding to said discrete steps; each of said groove means being angularly displaced about the axis of said member relative to the other groove means whereby only a selected one of said groove means may be aligned with said slot for each angular position of said member.

3. In a combination lock having a retractable bolt, movable operating means for retracting said bolt, and a movable latch normally engaging said bolt and holding the same against retraction, the improvement comprising; a slidable plate having means for releasing said latch from said bolt when said plate slides in one direction; at least one opening through said plate and a slot of less width than said opening and extending therefrom in the direction of movement of said plate; a member extending through said opening in a direction substantially perpendicular to said plate means for moving said member in said opening through a selected number of discrete steps; the dimension of said member in a direction transverse to said slot being greater than the width of said slot; tangential groove means in said member at a predetermined position therealong whereby movement of said member through a predetermined number of said discrete steps will place said groove means in the plane of said plate, and in alignment with said slot to permit said plate to slide past said member in a latch releasing direction with said slot embracing said member at said groove means.

4. The lock defined in claim 3 including spring means urging said plate to slide in said latch releasing direction; said operating means including a blocking element movable therewith and normally holding said plate against movement by said spring; said blocking element being retractable from blocking relation to said plate upon initial movement of said operating means to release said plate to said spring for initial movement thereby; and means on said plate for blocking operation of said means for moving said member through said opening in response to said initial movement of said plate.

5. The lock defined in claim 3 wherein said means for moving said member through said opening comprises a ratchet bar movable with said member, a manually operable pushbutton having a pawl engaging said ratchet bar; means for retracting said pushbutton and pawl; and a hold ing pawl engaging said ratchet bar for holding said member in discrete positions.

6. The lock defined in claim 3 wherein said member is rotatable about an axis generally perpendicular to said plate; means for rotating said member about said axis and for holding the same in a selected one of a plurality of angular positions; there being a plurality of said tangential groove means on said member, axially spaced therealong at distances corresponding to said discrete steps; each of said groove means being angularly displaced about the axis of said member relative to the other groove means whereby only a selected one of said groove means may be aligned with said slot.

'7. The lock defined in claim 6 wherein said member comprises a cylinder, said groove means each being a pair of parallel grooves arranged on opposite sides of said cylinder and adapted to slidably receive the respective opposite edges of said slot; said means for moving said member comprising a ratchet bar extending through said slot adjacent said cylinder and having means engaging the ends thereof whereby said bar and cylinder move together, a manually operable pushbutton having a pawl engaging said ratchet bar, means for retracting said pushbuiton and pawl, and a holding pawl engaging said ratchet bar for holding said member in discrete positions; both said pawls extending through said slot.

8, The lock defined in claim 6 including biasing means urging said member to .move in one direction through said opening; said means for moving said member through said discrete steps being arranged to advance said member in the other direction and including holding means for bolding said member, at each discrete step, against the action of said biasing means; and reset means operable by said movable operating means for disabling said holding means whereby said biasing means returns said member to a starting position.

9. The lock defined in claim 8 wherein said reset means is movable by said operating means to selectively slide said plate in a direction opposite said latch releasing direction; said holding means comprising a ratchet bar movable with said member and a pawl engageable with said ratchet bar; said plate having means thereon for disengaging said pawl from said ratchet bar when said plate is moved by said reset means.

References Cited UNITED STATES PATENTS 2,598,457 5/1952 Capdevila -3l3 MARVIN A. CHAMPION, Primary Examiner.

ROBERT L. WOLFE, Assistant Examiner. 

1. IN A COMBINATION LOCK HAVING A RETRACTABLE BOLT AND MEANS NORMALLY HOLDING SAID BOLT AGAINST RETRACTION, THE IMPROVEMENT COMPRISING; A PLATE MOUNTED FOR MOVEMENT IN THE PLANE CONTAINING ITS EDGES AND HAVING MEANS FOR RELEASING SAID BOLT FOR RETRACTION WHEN SAID PLATE MOVES IN ONE DIRECTION; AT LEAST ONE OPENING THROUGH SAID PLATE AND A SLOT OF LESS WIDTH THAN SAID OPENING AND EXTENDING THEREFROM IN THE DIRECTION OF MOVEMENT OF SAID PLATE; A MEMBER EXTENDING THROUGH SAID OPENING IN A DIRECTION SUBSTANTIALLY PERPENDICULAR TO SAID PLATE; MEANS FOR MOVING SAID MEMBER IN SAID OPENING THROUGH A SELECTED NUMBER OF DISCRETE STEPS; THE DIMENSION OF SAID MEMBER IN A DIRECTION TRANSVERSE TO SAID SLOT BEING GREATER THAN THE WIDTH OF SAID SLOT; TANGENTIAL GROOVE MEANS IN SAID MEMBER AT A PREDETERMINED POSITION THEREALONG WHEREBY MOVEMENT OF SAID MEMBER THROUGH A PREDETERMINED NUMBER OF SAID DISCRETE STEPS WILL PLACE SAID GROOVE MEANS IN SAID PLANE; AND IN ALIGNMENT WITH SAID SLOT TO PERMIT SAID PLATE TO SLIDE PAST SAID MEMBER IN A LATCH RELEASING DIRECTION WITH SAID SLOT EMBRACING SAID MEMBER AT SAID GROOVE MEANS. 